Recent content by alebruna

While studying for my exam I came across the addition of two angular momenta, in the simple case of ##J=L+S## where ##L## is the angular momentum operator and ##S## is the spin (in this case a fermion with ##s=1/2##). I have some doubts on the derivation of the basis and the eigenvalues. From...

I have a question about an example about the choice of the operators needed to describe a system, the text is reported below: "3D systems with ##H = (p_1^2+ p_2^2+ p_3^2)/(2m)## but no potential. Classically, the number of degrees of freedom is 6 corresponding to the six canonical variables xi...

So in this case ##(\psi_{\vec{k}},\psi_{\vec{q}})## indicates the projection of ##\psi_{\vec{k}}## on ##\psi_{\vec{q}}## and since in this case they are orthogonal the only possibility for which that projection exists (and it's also 1) is that \vec{k} and \vec{q} are equal. But since in this...

Thank you for your explanation, I think I understood better what we're talking about

My attachment comes from study material that our professor published on the site of university but it's not publicly available so I only have the pdf not a link. I'll put below the complete file. [Moderator's note: attachment deleted, see post #7.]

I'm an undergraduate trying to understand quantum physics. So, I'm trying to understant the plane wave basis for a general 3D box. I understood that the plane wave basis is used to define a period boundary to model real-world situations where the space in which the experiment is performed is...